Article

The effect of walking speed on superficial lower limb muscles, such as tibialis
anterior and triceps surae, is well established. However, there are no published
data available for tibialis posterior - a muscle that plays an important role in
controlling foot motion. The purpose of this study was to characterise the
electromyographic timing and amplitude of selected lower limb muscles across five
walking speeds. Thirty young adults were instructed to walk barefoot while
electromyographic activity was recorded from tibialis posterior and peroneus
longus via intramuscular electrodes, and medial gastrocnemius and tibialis
anterior via surface electrodes. At faster walking speeds, peak electromyographic
amplitude increased systematically during the contact and midstance/propulsion
phases. Changes in the time of peak amplitude were also observed for tibialis
posterior, tibialis anterior and peroneus longus activity; however, these were
muscle and phase specific. During contact phase, peak electromyographic amplitude
for tibialis posterior and peroneus longus was similar across very slow to slow
walking speeds. During midstance/propulsion phase, peak electromyographic
amplitude for tibialis posterior and medial gastrocnemius was similar across very
slow to slow walking speeds. These findings may reflect a relatively higher than
expected demand for peroneus longus and tibialis posterior to assist with
medio-lateral foot stability at very slow speeds. Similarly, peak amplitude of
medial gastrocnemius was also relatively unchanged at the very slow speed,
presumably to compensate for the reduced forward momentum. The data presented in
this study may serve as a reference for comparing similarly matched participants
with foot deformity and/or pathological gait.
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Langue : ANGLAIS